1. What font size is larger than .9em?
Anything greater than 0.9em e.g. 1em, 2em etc
2. Is there a heavier bold weight that I can use here?
Font weights can be specified in words (bold, bolder) or numbers (100 through to 900).
Just be aware that most browsers do not support all of the numeric font-weights. In fact I've only ever seen those numeric weights equivalent to 'normal' and 'bold' supported (100 and 600, respectively - I think).